class Student:
    def __init__(self, name, age, grade):
        self.name=name
        self.age=age
        self.grade=grade
    def say_hi(self):
        print('I am a student, my name is', self.name)

s1=Student('王子', 21, 3)
s1. say_hi()
print(s1. grade)
s2= Student('公主', 20, 2)
s2. say_hi()
print(s2. grade)
